Firmware upgrade fails.

Zyxel_JonasTan

If you encounter difficulties in completing a successful firmware upgrade, please verify whether your network environment can resolve "firmware.nebula.zyxel.com," as illustrated in the figure below:

Tool: Eg. Windows "Command prompt" (shortcut: windows+R > cmd > Enter)

If not, kindly modify your DNS settings to 8.8.8.8 or incorporate a rule in your firewall or router permitting access to the specified domain name "firmware.nebula.zyxel.com".

Note: "firmware.nebula.zyxel.com" utilizes port 443 for transmission; additional details can be found at this link.